Question

Which metal(s) can be used to produce electrons by the photoelectric effect from a given source of light?
A. Barium only
B. Barium and lithium
C. Lithium, tantalum, or tungsten
D. Tungsten or tantalum

Answer 1

Hint: The photoelectric effect occurs when light shines on a metal and causes electrons to be expelled from the metal's surface. Photoemission is another name for this process, and photoelectrons are the electrons that are emitted from the metal.Photoelectrons behave and behave like other electrons in terms of behaviour and attributes.

Complete step by step answer:
When a substance absorbs electromagnetic radiation, electrically charged particles are emitted from or within it, causing the photoelectric effect. The ejection of electrons from a metal plate when light falls on it is a common definition of the effect.
Photoelectric effect equation:
$K{E_{\max }} = hv - {W_ \circ }$
The minimum energy to knock out electrons
$KE \geqslant 0 \\
\Rightarrow hv > {W_ \circ } \\
\Rightarrow \dfrac{{hc}}{\lambda } > {W_ \circ }\,\,\,...........\left( 1 \right) \\ $
Here, available energy = $E = \dfrac{{hc}}{\lambda } = 2.75\,eV$
For photoelectric effect
${W_ \circ } < 2.75\,eV$ by (1)
From the table only true for $Ba$ and $Li$.

Hence, the correct option is B.

Note: Photoelectric devices have a number of advantages, including creating a current that is precisely proportional to light intensity and having a very fast response time. The photoelectric cell, often known as a photodiode, is a simple device. Originally, this was a phototube, a vacuum tube containing a cathode made of a metal with a small work function so that electrons would be easily emitted. The current released by the plate would be gathered by an anode held at a large positive voltage relative to the cathode.